Selective signaling system



1941- B. c. BELLOWS EI'AL SELECTIVE SIGNALING SYSTEM 2 Sheets-Sheet .1

Filed July 1, 1933 B.C.BELLOW$ AFGRENELL -IIIHI QQS 3.33

w? V w A TTORNE V 4 B. c. BELLOWS EI'AL ,36

SELECTIVE SIGNALING SYSTEM BCBELLGWS MENTOR? AFGRENELLY ,4 TTOR/VEV Patented Feb. 18, 1941 UNITED STATES PATENT OFFICE Grenell, Montclair, N.

J assignors to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application July 1, 1939, Serial No. 282,330

6 Claims.

This invention relates to improvements in signaling systems and more particularly to means for selectively controlling the operation, over a ringdown toll line, of linesignals located at different operators positions as, for example, at either so-called inward or through positions. In such system it is desirable that the originating operator, at one end of the line, be able to selectively signal, 1. e., light the line lamp, before either an inward or a throng operator at a distant toll office, depending on the nature of the connection desired.

A feature of the invention resides in means at the originating or outward operators positions for selectively applying to the line one or the other of two different signaling frequencies, for example, 20 and 1000 cycles, and in means at the distant end of the line selectively responsive to the transmitted frequency to actuate one or the other of two corresponding line signals located before different operators.

More specifically, the line at the originating or outward switchboard is terminated in two jacks, one of which may, for example, be designated in such a manner as to indicate that when it is seized a predetermined frequency will be transmitted to operate apparatus at the other end of the line to in turn cause the line signal at the inward position to be displayed whereas if the other jack of the pair is seized, it will be understood that another predetermined frequency will be transmitted to display the line signal at the through operators position. The invention will be understood from the following description and accompanying drawings, in which:

Fig. 1 represents one end of a two-way toll line L terminating at a toll office A in inward jacks Hill and IM and outward jacks I02 and Iii-3; and

Fig. 2 represents the other end of the same line terminating at a toll office B in inward jacks 285 and 23! and outward jacks 202 and 20.3.

Jacks I638 and 200 appear at terminating or so-called inward positions, jacks HM and 2M appear at switching or so-called through positions and jacks H12, I03, 282 and 203 appear at socalled outward positions. As both ends of the line L are identical, it will only be necessary for a complete understanding of the invention to trace the circuit operation in one direction for the two types of calls referred to previously, i e., terminating and through and therefore we will first trace a call originated by the outward operator at office A by way of jack Iii2 for a subscriber within the local exchange area of office B and reached therefrom either directly or over a trunk circuit by Way of jack 200 of the inward position and secondly we will trace the circuit operation for a call also originated at ofiice A, by way of jack I8 3, for a third toll office, and reached over a second toll line, neither of which is shown, 5 by way of jack 203 at ofiice B.

When the outward operator is in possession of the details of a call for a subscriber which is to be completed by the inward operator at toll office B, she inserts the plug M of her cord circuit in in jack I02 whereupon ringing current is automatically connected to the line and causes the line lamp 235 at ofiice B to light before the inward operator.

The circuit operation is as follows: When the i plug I014 is inserted in jack I02, battery on the sleeve of the plug causes operation of the sleeve relay Hi6 which in turn operates relay m1. Relay Ilil in closing its cont-acts I08 connects the sleeve of jack I03 in multiple with the normally connected sleeves of jacks I90, I01 and I 02.

Closure of contacts I09 of relay III'I operates relay Illi which opens the normally closed bridge across the line consisting of resistance NH and condenser M2 and closes its contacts II3 to light all the busy lamps H4, H5 and H6 at that end of the line and also operates relay I69 which disables the voice frequency receiving circuit R1 and prevents its false operation by speech.

When relay I01 closed its contacts I I1, it completed a circuit to step the selector brushes [I8 and M9 of the selector Sa, under control of interrupter I20. This circuit can be traced from battery, winding of magnet I2I, contacts I22 of relay I23, contacts II! of relay I01 and the upper 5 back contact of relay L2G to ground through interrupter I20. Stepping magnet I2I energizes and releases in step with the interrupter and moves the selector brushes forward in a clockwise direction. On its first step brush H8 ena gages the first contact of the bank, thereby connecting battery to the tip conductor I25 of the line to cause operation of the ringing relay I25 which connects ringing current to the toll line L. This circuit can be traced from battery, brush II8, contacts P2! of relay I23, tip conductor I25, left-hand winding of retard coil I35, and. winding of slow-release relay I34 to ground. Relay I34 operates and closes its contacts I512 thereby extending battery on the tip conductor I 25 to relay IYZ G by way of the normally closed front contacts of relay I53. Closure of the lower contacts of relay I34 short-circuits the left-hand winding of retard coil I35.

Magnet I2-I continues to step the brushes H 8 and M9 ahead and as the first three contacts of the left-hand bank are connected together, relay I26 will remain operated to continue ringing. When the selector brush I I8 steps ofi the third contact, relay I23 will release and ringingwill cease and soon thereafter relay I34 will release and on the fourth step brush I'eI9 will engage the fourth contact of the right-hand bank thereby completing a circuit to operate the release relay I23 in an obvious circuit. Operation of relay 023 opens its contacts I122 thereby disconnecting the stepping magnet I ZII from the interrupter and stopping the forward movement of the selector.

Relay I23 also closes its contacts I33 thereby energizing relay I 24 and disconnecting the interrupter at another point. Relay I24 thereupon locks in an energized condition over its inner lower contact to ground at the lowermost contacts of relay I0'I which relay was operated when the plug was inserted in jack I02. Further, relay I23 closes its contacts I3I thereby completing an obvious circuit to operate the release magnet I32 which causes the selector to restore to normal in a counter-clockwise direction.

Restoration of the selector to normal opens the circuit for relay I23 which thereupon releases. Operation of relay I24 also connects battery, at its lowermost contact, to supplement the battery connected at contacts I I3 of relay I I0 to the busy lamp circuit, also relay I69. Relays I06, I01, H0 and I24 are now operated and held under control of the sleeve circuit of plug I04 and jack It will be noted that when battery was removed from conductor I25 on the fourth step of the selector, relay I34 was deenergized but due to its slow-release characteristics, it held the ring conductor open at its contacts I36 and maintained a short circuit across the repeating coil at contacts I39 for a sufficient interval, before connecting the line through to the operators telephone circuit to obviate objectionable clicks therein due to the charge built up in the line by the ringing current.

Now, directing attention to office B (Fig. 2), when ringing current is received over the toll line, it causes the operation of the bridged ringing relay 240 which in turn releases relay 253 to operate relay 24I, the circuit for which can be traced from battery, back contacts of relay 253, contacts 242 of relay 234 and the middle winding of relay 24I to ground. Relay MI in operating closes its lowermost contacts thereby operating relay 224 which disables selector Sb by disconnecting the interrupter 220 thereby preventing a ringing impulse being transmitted toward ofiice A when the inward operator answers the call by inserting plug 243 in jack 20. Operation of relay 224 also connects battery at its lowermost contact to light all the busy lamps 2I4, 2I5 and 2I3, associated with this line at office B and also operates relay 269 to disable the voice frequency ringer R1 to prevent its operation by speech. Relay MI in operating also closes its contacts 244 thereby completing a circuit to operate relay 245 which can be traced from battery, contacts 246 of relay 2I0, winding and contact 24? of relay 245, contacts 244 of relay 24I, contacts 248 of relay 249 and line lamp 205 to ground. Relay 245 is sufirciently sensitive to operate in series with lamp 205 but lamp 205 does not burn at full brilliancy in series with this relay. When relay 245 operates, it closes its lower contact thereby completing a locking circuit for relay 24I and at its contacts 250 connects direct battery to the circuit previously traced through lamp 205, which lamp thereupon lights to full brilliancy as an indication to the inward operator of the arrival of a call. Relay 245 itself locks operated over its contacts 25L Relays MI, 245 and 224 are now operated and held in this condition pending the operators answer. the inward operator observes the lighted line lamp 205 she inserts the plug 243 of one of her cord circuits in jack 200 thereby causing the operationofrelay206which operates relay 20'! which in turn operates relay 2I0. Relay 2I0 in operating opens its contacts 240 thereby releasing relay 245 which extinguishes the line lamp by opening its contacts 250. Relay 245 also opens its lower contacts thereby releasing relay 24I The release of relay 24I, however, does not release relay 224 as this latter relay is now locked over its lower contact to ground at the lowermost contacts of relay 202. Operation of relay 207 closes its contacts 208 thereby connecting the sleeve of the jack 203 to the sleeve of jack 200 thus making this jack busy to any subsequent attempt to connect a cord circuit thereto. Sleeves of jacks 20I and 202 are normally connected to the sleeve of jack 200.

Relay 2I0 connects battery at its contacts 2I3 to the busy lamps 2I4, 2I5 and 2I6 in parallel with the battery supplied over the lower contacts of relay 224 and also holds relay 239 operated.

When the operators at both ends of the line disconnect, the respective ends of the circuit restore to normal.

As previously mentioned, both ends of the circuit are identical and, therefore, the initiation of a call at ofilce B for the inward operator at ofiice A will be effected in the same manner as just described except in the reversed direction.

Calling a through operator Now let us assume that the outward operator at oifice A desires to be connected to a third toll office distant from oifice B and reached via office B over a second toll line, not shown, which type of switch connection is handled by a so-called through operator. Knowing that the call is for a toll point beyond omce B and therefore must be switched there by a so-called through or switching operator, the outward operator at office A inserts the plug I 04 of her cord circuit in the so-called via jack I03 instead of in jack I02 as before.

When the plug is inserted in jack I03, relay I55 operates in an obvious circuit which in turn operates slow-release relay I28. Relay I28 opens its contacts I55 and closes its contacts I51 thereby disconnecting the jack I03 from the line and connecting a termination consisting of resistance I58 and condenser I59 across the tip and ring of the jack and, therefore, across any line which may be connected thereto by means of plug I04.

At its contacts I60, relay I28 closes a circuit to energize the stepping magnet I2I of selector So in the following circuit, battery, winding of magnet I 2!, contacts I22 of relay I23, contacts I60 of relay I28 and upper back contacts of relay I24 to ground through interrupter I20. On the first closure of the interrupter I20, magnet I 2I moves selector brush II8 into engagement with the first contact of the selector bank thereby closing a circuit to operate relay I30, the circuit for which includes contacts IBI of relay I28. At the same time oil-normal contacts I 62 of the selector are closed thereby providing a locking ground for relay I28 which, therefore,

When

cannot release until the selector has been restored to normal. During the first three steps of the selector, ground will remain connected to relay I30 which relay opens the tip and ring at its contacts I29 and I63 and connects the voice frequency source of alternating current I64 (which may be of the order of 1000 cycles) to the transformer I38 at contacts I65 and I66, over the back contacts of relay I26. Relay I40 which is bridged across this circuit does not respond to the frequncy of source I64 due to its electrical characteristics.

When the brush II8 moves off the third contact of the switch, relay I30 releases which disconnects the source I64 from the line and reconnects the conductors I25 and I31 to the line through the transformer I38.

When brush II9 of the selector makes contact with the fourth terminal of its associated bank, the slow-to-release relay I23 operates which closes its contacts I33 to operate relay I24 thereby disconnecting the interrupter I20 from the stepping magnet I2I. At its lowermost contacts, relay I24 lights the busy lamps H4, H5 and H6 and also operates relay I69 whose purpose has already been mentioned. Operation of relay I23 also closes its contacts I3I which energizes the release magnet I32 and causes the selector to restore to normal thereby deenergizing relay I23 which, however, is slow to release and holds operated for a short interval. When the selector restores, the off-normal contacts I62 are opened thereby removing the holding ground for relay I28. Further, relay I23, on operating, closes its contacts I61 thereby operating relay I01 which opens its contacts I68 and opens the circuit between the sleeve of jack I03 and relay I55 which thereupon releases in turn releasing relay I28 as this relay now has no locking ground due to the release of the selector and the opening of the off-normal contacts. Relay I01 also closes its contacts I08 thereby connecting the sleeve of jack I03 to relay I06 which now operates and holds relay I01 operated which otherwise would release clue to the release of relay I23. Relay I01 in operating closes a circuit to operate relay H0 which removes the termination consisting of resistance III and condenser II2 from across the conductors I25 and I31 and at its contacts H3 closes a circuit to insure the continued lighting of busy lamps H4, H5 and H6 and operation of relay I69. When relay I01 operated it also closed its lowermost contacts to hold relay I24 operated thereby disabling the selector stepping circuit as long as the plug remains in jack I03.

It will be noted that release of relay I28 recloses its contacts I56 and opens contacts I51 thereby connecting the tip conductor through to the tip of the jack tion consisting of resistance I58 and condenser I59 from across the tip and ring.

Relays I06, I01, IIO, I24 and I69 are now op-.

erated and remain so during the continuance of the call.

When the voice frequency signaling current connected to the line by operation of relay I30 arrives at the other end of the line (Fig. 2), it passes through transformer 238, over the normal back contacts of relay 226, contacts 229 and 263 of relay 239 and back contacts of relay 269 to the right-hand winding of transformer 210 of the so-called voice frequency ringer R2 whose method of operation is well known, it being sufficient to point out that the incoming wave is amplified by the vacuum tube and removing the termina- 2H and transmitted through transformer 212 to the rectifier 213 which delivers a unidirectional current to operate relay 214 which relay in operating removes ground from normally operated relay 215 which presently releases to connect battery at its back contact to operate relay 249' in a circuit including contacts 236 of relay 234, left winding of retard coil 235 and lower winding of relay 249 to ground.

Operation of relay 249 closes its contacts 216 thereby operating relay 24I and opening its contacts 249 and closing its contacts 211 thereby transferring the previously described lamp lighting circuit from lamp 205 at the regular inward position, to lamp 218 at the through position, the operation of which is as follows: Battery is first connected over contacts 2460f relay 2I0 through the winding of relay 245 and its contacts 241, contacts 244 of relay 24I, contacts 211 of relay 249 and lamp 218 to ground which lamp does not light to full brilliancy at this time due to the resistance ofv relay 245 which relay, however, receives sufficient current to operate thereby connecting direct battery over its contacts 250 to the circuit just described to light lamp 218 to full brilliancy. Relay 245 also looks up at its contact 25I to battery and at its lower contacts provides holding battery to lock relays HI and 249.

Relay 24I in operating also operates relay 224 thereby disconnecting the interrupter to prevent operating the selector Sb when. the operator answers. Relay 224 in operating connects battery at its lower contacts to light the busy lamps 2I4, 255 and 2I6' and also to operate relay 269. Operation of relay 249 opens its uppermost contact thereby opening the sleeve circuit of the regular inward jack 200 thereby preventing the regular inward operator from extinguishing the line lamp 218 in case she should connect to the line at this time.

When the through operator observes the lighted lamp 218 she inserts plug 219 of one of her cord circuits in jack 20I, thereby operating relay 206 which in turn operates relay 201. Relay 201 closes its contacts 208 thereby connecting the sleeve of jack 203 to the sleeves of jacks 20I and 202, and thus jacks 202 and 203 will test busy as long as the plug is in jack 20I. Relay 261 also closes its contacts 206 thereby operating relay 2I0 which opens its contacts 246 thereby releasing relays 245, 249 and MI and extinguishes the line lamp 218. Relays 224 and 269, however, do not release as they are held operated by ground connected at the lowermost contacts of relay I01.

Disconnection by either operator restores the circuit, at that end of the line, to normal.

What is claimed is:

1. In a selective signaling system, a line, a plurality of operators positions at one end of said line, a corresponding number of jacks connected in multiple to the other end of the line, a signal device at each of said positions, an operators cord circuit adapted to cooperate with any one of said jacks, a generator of voice frequency alternating current having an output circuit, means responsive to the connection of said cord circuit with one of said jacks to momentarily connect said output circuit to the line and thereafter prevent its reconnection during the period the cord is connected to the jack, a second source of alternating current of a different frequency adapted to be connected to said line when said cord circuit is connected to another of said jacks, means at the other end'of the line responsive to the momentary transmission thereover of said voice frequency current to energize one of said signal devices, and means responsive to transmission of said different frequency to energize another of said signal devices.

2. In a selective signaling system, a line, a plurality of operators positions at one end of said line, a corresponding number of jacks connected in multiple to the other end of the line, a signal device at each of said positions, a plurality of sources of alternating current of difierent frequency corresponding in number tothe number of signal devices, an operators cord circuit at the jack end of said line, means automatically responsive to the connection of said cord circuit to one of said jacks to momentarily connect one of said frequency sources thereto and thereafter prevent its reconnection during the period the cord is connected and means responsive to connection of said cord circuit to another of the jacks to connect another of said frequency sources to the line, translating means at the other end of the line individual and responsive to each of said different frequencies, and means individually responsive to operation of each of said translating means to selectively actuate a different one of said signal devices.

3. In a selective signaling system, a two-way ring-down toll line, a plurality of answering jacks connected in multiple to said line at each end thereof, a corresponding number of calling jacks connected in multiple to each end of said line, a line lamp associated with each answering jack, different frequency sources of alternating current at each end of the line individual to each line lamp at the other end of the line, an operators cord circuit at each end of the line adapted to be connected to any one of said jacks thereat, means automatically responsive to the connection of a cord circuit to any one of said calling jacks to selectively cause the momentary connection of a particular source to the line, and thereafter prevent any of said frequency sources from being connected, translation means at each end of the line individual and responsive to each of said different frequencies at the other end of the line, means individually responsive to operation of each of said translation means to selectively light the line lamp corresponding to the particular frequency transmitted, and means responsive to the connection of a cord circuit to the answering jack corresponding to the lighted lamp to prevent a different frequency transmitted over the line from lighting another line lamp at that end.

4. In a selective signaling system, a line, a plurality of operators positions at one end of said line, a corresponding number of jacks connected in multiple to the other end of the line, a signal device at each of said positions, an operators cord circuit adapted to cooperate with any one of said jacks, a generator of voice frequency alternating current adapted to have its output circuit connected to said line, means including a selector switch responsive to the connection of said cord circuit with one of said jacks to momentarily connect said output circuit to the line and thereafter prevent its reconnection during the period the cord is connected to the jack, a second source of alternating current of a different frequency, and other means including said same selector switch adapted to connect the second source to said line when said cord circuit is connected to another of said jacks, means at the other end of the line responsive to the momentary transmission thereover of said voice frequency current to energize one of said signal devices, and means responsive to the transmission of said different frequency to energize another of said signal devices.

5. In a selective signaling system, a toll line, two operators positions at one end of said line, a signal device at each of said positions, a source of alternating current below the voice frequency range, and a source within the voice range, means for selectively connecting either one of said sources to the line, translating means associated with said line individual and responsive to each of said different frequencies, means individually responsive to said translating means to selectively energize said signal devices, and other means operated by the response of either translating means to dissociate the voice frequency translating means from the line.

6. In a selective signaling system, a two-Way ring-down toll line, a plurality of answering jacks connected in multiple to said line at each end thereof, a corresponding number of calling jacks connected in multiple to each end of said line, a line lamp associated with each answering jack, a source of voice frequency alternating current and a source of alternating current of a frequency below the voice range at each end of the line, each of said sources being individual to one of the line lamps at the other end of the line, an operators cord circuit at each end of the line adapted to be connected to any one of said jacks thereat, means automatically responsive to the connection of a cord circuit to any one of said calling jacks to selectively cause the momentary connection of a particular source to the line and prevent another frequency source from being connected, translation means at each end of the line, individual and responsive to each of said different frequencies at the other end of the line and means individually responsive to operation of each of said translation means to selectively light the line lamp corresponding to the particular frequency transmitted, means in each end of the line for disabling the voice frequency translation means thereat, said means at an an swering end being operated by the response of either translating means thereat and the corresponding means at a calling end being operated in response to connection of the cord circuit to either calling jack.

BRIAN C. BELLOWS. ARTHUR F. GRENELL. 

